CVE-2026-26861 - Vulnerability Analysis

Overview

CleverTap Web SDK <= 1.15.2 contains a stored XSS caused by insufficient origin validation in handleCustomHtmlPreviewPostMessageEvent using includes() in src/util/campaignRender/nativeDisplay.js, letting attackers execute scripts via crafted postMessage, exploit requires attacker to send crafted postMessage from a subdomain.

Severity & Score

Impact

Attackers can execute arbitrary scripts in users' browsers, leading to session hijacking or data theft.

Mitigation

Update to a version later than 1.15.2 or the latest available version.

References

• https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121
• https://github.com/CleverTap/clevertap-web-sdk/issues/424
• https://github.com/CleverTap/clevertap-web-sdk/pull/417

Social Media Activity(1 post)

TheHackerWire

@thehackerwire

Feb 28, 2026

🟠 CVE-2026-26861 - High (8.3) CleverTap Web SDK version 1.15.2 and earlier is vulnerable to Cross-Site Scripting (XSS) via window.postMessage. The handleCustomHtmlPreviewPostMessageEvent function in src/util/campaignRender/nativeDisplay.js performs insufficient origin validati... 🔗 https://www.thehackerwire.com/vulnerability/CVE-2026-26861/ #CVE #vulnerability #infosec #cybersecurity #security #Tenda #patchstack

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